Time, Speed & Distance
Aptitude

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Q.

Walking at the rate of 4 kmph a man cover certain distance in 2 hr 45 min. Running at a speed of 16.5 kmph the man will cover the same distance in.

 A.

12 min

 B.

25 min

 C.

40 min

 D.

60 min

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Solution:
Option(C) is correct

Distance = Speed × time

Here time = 2hr 45 min = \(\dfrac{11}{4}\) hr

Distance = \(4\times \dfrac{11}{4}=11\) km

New Speed =16.5 kmph

Therefore time = \(\dfrac{D}{S}=\dfrac{11}{16.5}=\textbf{40 min}\)

Edit: For an alternative solution, check Debanjan's comment.


(14) Comment(s)


Jeni
 ()

Using proportion concept

Speed and Time are inversely proportional.

S1 = 4km/hr

S2= 16.5km/hr So multiplying factor 16.5/4 (multiplying factor = new value/ old value)

Hence for time, multiplying factor becomes 4/16`5 (as speed and time are inversely proportional)

T1* 4/16.5 = T2

2hr 45 min * 4/16.5 = T2

11/4 * 4/16.5 = 11/16.5 = 40 min



Bighneswar Behera
 ()

s=4 kmph

t=2hrs 45 min = 165

d=x

d=165*4=660

if the distance is 660 he will travel 16.5 in??

660/16.5=40



Kakati Ravi Teja
 ()

How did Here time = 2hr 45 min became 11/4 hr???


Jeni
 ()

First convert the minute portion ie, 45 minutes in 2 hrs 45 minutes to hour

we add the the result with the existing 2 hours to make the unit same ie in HOURS only

2 hr 45 min = 2 hr + 45/60 hr (1 hr = 60 min , so 45 min = 45/60 hr)

= 2 hr + 9/12 hr

= 33/11 hr

=11/4 hr

Hope it helps


Poonam
 ()

debanjan solved the question but how 2/3 came ? can any 1 explain pls



Vaishali
 ()

in that last step how did u get the ans 11/16.5 = 40 ??????


Devinathan
 ()

You are finding the time taken in minutes...11/16.5= 0.66 and 0.66*60=40 min


Arpan Bansal
 ()

Alternate solution can be:

V1/V2=T2/TI

4 Kmph/ 16.5 Kmph = T2 / 165 Min 2hr 45min = 165 min

After solving

T2 = 40 min



Akshay
 ()

No need to find the distance ,as speed ti increased approx 4 time so the time is reduced by 1/4 so simply 4/14.5 * 165 min= 40 min .I think simple approach



Unknown
 ()

distance cover = 4*165=x*165/10

x=40 min



NEHA
 ()

what is V1, V2? AND HOW IT IS 4/33/2?



Balaji
 ()

in above explanation how it will come 2hr 45min=11/4hr ?


Zaved
 ()

2hr 45min = 2hr +$\dfrac{3}{4}$ hr

$= 2=\dfrac{3}{4}$ hr

$=\dfrac{11}{4}$ hr.

Hope that helps.


Debanjan
 ()

It is much easier to use the formula $\dfrac{V_1}{V_2}=\dfrac{T_2}{T_1}$

or, $\dfrac{4}{33/2}=\dfrac{T_2}{11/4}$

or $T_2 = \dfrac{2}{3}$ hour

$= \dfrac{2}{3}\times 60\text{ min}$

$=\textbf{40min}$